JPH06143413A - Thermoplastic polyurethane multilayer film and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent formation of a pinhole, eliminate leakage of liquid at the time of injection of urethane and suppress blocking by manufacturing a thermoplastic polyurethane multilayer film by specific composition and specific combination. CONSTITUTION:A thermoplastic polyurethane multilayer film having a layer constituted of (a) 35-90wt.% thermoplastic polyurethane resin, (b) 5-60wt.% polyethylene resin and (c) 5-40wt.% ethylene-propylene copolymer rubber and a layer constituted of the thermoplastic polyurethane resin or (a) 35-90wt.% thermoplastic polyurethane resin, (b) 5-60wt.% polyethylene resin and (c) 5-40wt.% ethylene-propylene copolymer rubber, is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyurethane-based multi-layer film and a method for producing the same, for example, by laminating it with a backup film or a woven or non-woven fabric of polyurethane injection type integrally molded automobile chairs and furniture. The present invention relates to a thermoplastic polyurethane-based multi-layer film that can be used as a skin material and the like, and particularly to an inflation film and a method for producing the same.

[0002]

2. Description of the Related Art Thermoplastic polyurethane elastomers are
Since it has high tackiness, is easy to block, and has a low melt tension, it is difficult to form a film by the inflation method by itself. For that purpose, for the purpose of preventing adhesion and reinforcement on the inside (inner layer), a carrier layer is provided with a polyethylene resin or the like and coextrusion is performed, and after or after secondary processing such as printing, laminating, or pressure-sensitive adhesive coating. A method of peeling a carrier layer to obtain a thermoplastic polyurethane elastomer single layer film is generally known. However, this method is uneconomical, such as an increase in the peeling step of the carrier layer (carrier sheet) and waste of the carrier sheet after peeling.
Further, as described above, since the melt tension of the thermoplastic polyurethane resin is small and its temperature dependence is large, the range of selection of conditions during film formation is narrow, and therefore,
There is also a problem that the film forming stability of the film is not stable, it is difficult to form a thin film, and it is impossible to stably obtain a long wound film. On the other hand, since polyurethane-based resin has hygroscopicity,
During film formation, pinholes are likely to occur due to moisture. That is, this pinhole is usually generated by adsorbed moisture, gel content and the like. In particular, in the case of polyurethane, since it has hygroscopicity, it is easy for pinholes to occur due to moisture, and if there is a pinhole, when using it as a backup film when injecting urethane as described above, liquid leakage from the pinhole location There is a problem that will happen. Further, in the film formation by the inflation method, it is also conducted to mix a large amount of an inorganic filler in the resin, but the characteristics of the thermoplastic polyurethane resin are easily damaged, and addition of the inorganic filler is not recommended. There is also the problem of being uneconomical. As a resin composition for improving the moldability of a thermoplastic polyurethane resin film, for example, a composition comprising soluble polyurethane and / or thermoplastic polyurethane obtained by mixing a specific ethylene copolymer with thermoplastic polyurethane (Japanese Patent Laid-Open No. No. 76165), a resin composition containing a thermoplastic urethane elastomer and an acid-containing thermoplastic olefin copolymer having an acid value of 2 to 100 (Japanese Patent Laid-Open No. 61-271351) and the like have been proposed. The thermoplastic polyurethane resin composition of (1) is recognized to have an improved effect of suppressing blocking and improving the moldability of the film, but it is not always sufficient and there is room for improvement.

[0003]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the prior art, prevents pinholes, and improves secondary workability without liquid leakage during urethane injection.
Blocking is suppressed, handleability is improved, moldability is improved, film thinning and film molding can be performed stably, and moreover, quality-stable products are made faster due to lower cost. It is another object of the present invention to provide a technique capable of improving the moldability of a film without impairing the properties of the thermoplastic polyurethane resin.

[0004]

According to the present invention, (a) a thermoplastic polyurethane resin (35 to 90% by weight), (b) a polyethylene resin (5 to 60% by weight) and (c) an ethylene-propylene copolymer type rubber (5) are used. 40 wt% layer (hereinafter sometimes referred to as A layer), and thermoplastic polyurethane resin or (a) thermoplastic polyurethane resin 35-9
0% by weight, (b) polyethylene resin 5 to 60% by weight, and (c) ethylene-propylene copolymer rubber 5 to 40
A layer composed of 10% by weight (hereinafter sometimes referred to as B layer)
A thermoplastic polyurethane-based multilayer film, and (a) a thermoplastic polyurethane resin (35 to 90% by weight), and (b) a polyethylene-based resin (5).
A layer consisting of 60% by weight and (c) 5-40% by weight of ethylene-propylene copolymer rubber, thermoplastic polyurethane resin or (a) thermoplastic polyurethane resin 35
To 90% by weight, (b) polyethylene resin 5 to 60% by weight, and (c) ethylene-propylene copolymer rubber 5 to
A gist of the method is a method for producing a thermoplastic polyurethane-based multilayer film, which comprises co-extruding and laminating a B layer consisting of 40% by weight, and in a preferred embodiment, the A layer is an inner layer and the B layer is an outer layer. An inflation film by extrusion and a method for producing the same.

The present invention will be described in detail below. The thermoplastic polyurethane resin (a) constituting the layer A (inner layer in the case of an inflation film) of the thermoplastic polyurethane-based multilayer film according to the present invention is an adipate-based, polyether-based, polycaprolactone-based, polyester-based polyurethane or the like. An example is an elastomer. Among these, adipate-based and polycarbonate-based resins are preferable in view of compatibility with the (b) polyethylene-based resin. Such a thermoplastic polyurethane elastomer has a JISA hardness of 80 to 100 or a softening point of 9
It is preferably about 0 to 140 ° C.

The polyethylene resin (b) constituting the layer A (inner layer in the case of an inflation film) of the thermoplastic polyurethane-based multilayer film according to the present invention is
Ethylene homopolymer or ethylene-based 2
Examples thereof include copolymers with 0% by weight or less of vinyl compounds and the like. Specific examples of the polyethylene resin include low density polyethylene, linear low density polyethylene, medium and high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and the like. The melt index (MI,
190 ° C, load 2,16 kg) is 0.05 to 20 g /
10 minutes is preferable, and more preferably 0.1-0.6 g /
10 minutes. The ethylene-vinyl acetate copolymer preferably has a vinyl acetate content of 5 to 25% by weight, more preferably 5 to 15% by weight, and the melt index (MI, 190 ° C., load 2,16 kg) is 0. 1-2
0 g / 10 minutes is preferable, and more preferably 1 to 5 g / 1.
0 minutes.

In the present invention, ethylene-propylene copolymer rubber (EPR) is used as the (c) ethylene-propylene copolymer rubber constituting the layer A (inner layer in the case of inflation film) of the thermoplastic polyurethane multi-layer film. And an ethylene-propylene-diene copolymer rubber (EPDM) obtained by copolymerizing a diene compound therewith. The ethylene-propylene copolymer rubber is
The ethylene content is preferably 50 to 90 mol%, and the propylene content is preferably 50 to 10 mol%. More preferable ranges are 70 to 80 mol% for ethylene and 30 to 20 mol% for propylene. In the case of ethylene-propylene-diene copolymer rubber (EPDM), examples of the diene compound include ethylidene norbornene, dicyclopentadiene and 1,4-hexadiene. Among such ethylene-propylene copolymer rubbers, ethylene-propylene-diene copolymer rubber is preferable. The melt flow rate (MI, 190 ° C, 2,16 kg load) of ethylene-propylene copolymer rubber is
It is preferably 0.1 to 5.0 g / 10 minutes, more preferably 0.3 to 1.0 g / 10 minutes.

The blending ratio of each component in the thermoplastic polyurethane resin composition is as follows: (a) the thermoplastic polyurethane resin is 35 to 90% by weight, preferably 45 to 80% by weight, and (b) the polyethylene resin is 5 to 60%. % By weight, preferably 10-40% by weight, and 5-40% by weight of (c) ethylene-propylene copolymer rubber, preferably 10-%.
It is 20% by weight. The thermoplastic polyurethane resin is 3
If it is less than 5% by weight, the properties of the polyurethane elastomer are lost, and the properties of polyurethane, such as abrasion resistance and mechanical strength, are deteriorated. On the other hand, when it exceeds 90% by weight, there are problems such as blocking during film formation of the film and lack of film formation stability. If the polyethylene resin is less than 5% by weight, blocking will occur during film formation. On the other hand, if it exceeds 60% by weight, the properties of the polyurethane elastomer are impaired, and the properties of polyurethane, such as abrasion resistance and mechanical strength, are also reduced. Further, when the ethylene-propylene copolymer rubber is less than 5% by weight, the melt tension is not sufficiently imparted and the stability in film formation is insufficient, while when it exceeds 40% by weight, blocking may occur. Also, the abrasion resistance and mechanical strength, which are characteristics of polyurethane, are reduced. In addition, in the present invention, an antioxidant, an ultraviolet absorber, a colorant, an inorganic filler and the like can be appropriately blended in addition to the above-mentioned respective components.

Next, the B layer (outer layer in the case of an inflation film) constituting the thermoplastic polyurethane-based multilayer film of the present invention will be described. The B layer (outer layer) is the same thermoplastic polyurethane resin composition as the thermoplastic polyurethane resin composition constituting the A layer (inner layer) of the above-mentioned thermoplastic polyurethane-based multilayer film, that is, (a) thermoplastic polyurethane resin. The composition may be composed of 35 to 90% by weight, (b) polyethylene resin 5 to 60% by weight, and (c) ethylene-propylene copolymer type rubber 5 to 40% by weight, or the thermoplastic resin. It may consist of a polyurethane resin alone.

Next, an example of the method for producing the thermoplastic polyurethane-based multilayer film of the present invention will be described based on the inflation method with reference to the drawings. The thermoplastic polyurethane resin composition constituting the inner and outer layers of the thermoplastic polyurethane-based multi-layer inflation film of the present invention comprises the above resin components and, if necessary, other components added, for example, a Hensiel mixer or a high speed mixer. Is preliminarily dry-blended and then heated, for example 180-
It is obtained by melt-kneading at about 220 ° C. using an extruder or the like and extruding into pellets. Using these pelletized thermoplastic polyurethane resin compositions, a multilayer film is produced by co-extrusion of a multilayer film as shown in FIG. 1, for example. In FIG. 1, 1 is an inner layer extruder, 2 is an outer layer extruder, 3 is a die, 4 is a bubble, 5 is a bubble inner layer, 6 is a bubble outer layer, and 7 is a nip. As shown in the drawing, the inner and outer layers 5, 6 are co-extruded from the extruders 1, 2 and air is fed into the bubble 4 from the arrow direction,
It is inflated, crushed into a flat shape at the nip 7, and wound up by a winding device. When the thermoplastic polyurethane resin composition is used for the inner layer 5 and the thermoplastic polyurethane resin alone is used for the outer layer, coextrusion can be carried out in the same manner to obtain a multilayer inflation film. Incidentally, in the case of molding as a tube-shaped film by the inflation method, it is possible to perform stretching in a well-balanced manner in the longitudinal and lateral directions in one step,
In addition, the air-cooled inflation method capable of high-speed molding with a thin film is preferable from the viewpoint of productivity. In the inflation molding method using the air cooling method, the resin temperature is 180 to 220.
It is preferable to carry out at a blow ratio in the range of 2.0 to 5.0. As a result, a film having a thickness of about 10 to 100 μm can be obtained. The thickness of the film is usually 10 to 100 μm. In the present invention, multi-layer coextrusion by a T-die extruder, extrusion lamination in which one composition is melt-extruded and laminated on the other film, or a lamination method of flat films may be used. In addition, although a two-layer structure has been described above as an example, a multi-layer structure of three or more layers may be used, and in that case, a layer of another type is further laminated in addition to the layers described above within a range not impairing the features of the present invention. It may be one.

[0011]

The function of the present invention will be described below.
As mentioned above, since polyurethane-based resins have hygroscopicity, they tend to have pinholes due to moisture during film formation. If pinholes are present, for example, when using them as backup films when pouring urethane, the There is a problem that liquid leaks from the hole. According to the study by the present inventors, it has been found that the formation of pinholes can be prevented by using a multi-layer film formed by multi-layer coextrusion of two or more layers as in the present invention. However, in the case of such multi-layer coextrusion, the thermoplastic polyurethane elastomers are sticky to each other. Therefore, in the case of the inflation method, it is necessary to consider the blocking resistance of the inner layer. However, the thermoplastic polyurethane resin composition used to form the thermoplastic polyurethane-based multilayer film of the present invention has low blocking properties and can prevent blocking even when pressed by a nip during inflation molding. Therefore, in the present invention, by using the thermoplastic polyurethane resin composition for the inner layer 5, it is possible to prevent the inner layers from being blocked by the nip during inflation molding. And
As described above, in general, since the thermoplastic polyurethane elastomer is tacky, it is necessary to consider the blocking resistance of its inner layer, but in the present invention, blocking between the thermoplastic polyurethane elastomers by the nip during inflation molding is required. Can be prevented. In the present invention, if the inner layer 5 is the above resin composition, the outer layer 6 may be the same resin composition as the inner layer 5 or may be thermoplastic polyurethane alone. However, the inner layer resin composition is slightly inferior in strength and abrasion resistance to the extent that it contains less urethane component than the thermoplastic polyurethane alone. The thermoplastic polyurethane resin is high in strength and particularly excellent in abrasion resistance, but is a considerably expensive resin. Therefore, in the case of applying to a skin material that requires sufficient characteristics of urethane resin, using thermoplastic polyurethane alone for the outer layer and forming a thin film, and using the above composition for the inner layer, it is possible to obtain the desired physical properties at low cost. Things are obtained. On the other hand, the thermoplastic polyurethane resin composition used in the present invention has a characteristic that film forming stability is good. The composition in which polyethylene is mixed with the thermoplastic polyurethane resin has an improved melt tension as compared with the thermoplastic polyurethane resin alone. This is considered to be due to the melt tension of polyethylene. However,
The melt tension of polyethylene has a large temperature dependency, and its decrease is remarkable when the temperature rises. In addition, the blending of polyethylene also improves blocking resistance. The composition comprising the thermoplastic polyurethane resin, the polyethylene resin and the ethylene-propylene copolymer rubber of the present invention has a small temperature dependence and a small decrease in melt tension even at a relatively high temperature. Therefore, stable thermoforming processing can be performed without significantly impairing the properties of the thermoplastic polyurethane resin, and film forming stability can be imparted during film forming, and film forming particularly in the air-cooled inflation method Bubbles required for speeding up and speeding up the molding are stable, and long winding is possible. Furthermore, in the present invention, the carrier sheet is unnecessary from the above, the peeling step is not necessary, the process is simplified, and the blocking property can be reduced without impairing the properties of the thermoplastic polyurethane resin, and the moldability is improved. Can be planned.

[0012]

EXAMPLES The present invention will now be described in more detail with reference to examples. The outer layer B used in Table 1 below is
An adipate-type thermoplastic polyurethane resin having a density of 1.19 g / cm ³ and a softening point of 120 ° C. was used as the thermoplastic polyurethane resin. The inner layer A is made of the above-mentioned thermoplastic polyurethane resin and ethylene-propylene copolymer rubber (EPDM, propylene content 27% by weight, iodine 12, Mooney viscosity (120
50 ° C.) and polyethylene resin (low density polyethylene LDPE, density 0.923 g / cm ³ , MI
0.8 g / min. No.)) and 45/30/25 in a ratio of 45/30/25. Examples 1 to 3 With the layer constitution ratio (outer layer / inner layer) shown in Table 1, the thermoplastic polyurethane resin, polyethylene resin and ethylene-propylene copolymer rubber constituting the inner layer A were dry blended with a spar mixer, While extruding from the inner layer extruder of the air-cooled inflation film molding apparatus, the outer layer B extruder was supplied with the thermoplastic polyurethane resin constituting the outer layer B, and coextruded under the film forming conditions shown in Table 1. A layer inflation film was formed. Comparative Examples 1 to 3 Example 1 except that the resin constitution and layer constitution shown in Table 1 were used.
The inflation film was molded according to the above. The film forming properties, pinhole properties, moisture permeability, and tensile strength of each of the obtained films were determined, and the results are shown in Table 1. The test methods in Examples and Comparative Examples are as follows. (1) Bubble stability: Bubbles during inflation film formation were observed and their degree was observed. (2) Opening property of tube: The opening portion of the inflation film was observed and the degree of opening was observed. In addition, in the case of inflation using only the thermoplastic polyurethane resin in Comparative Example 1, because of the film blockin,
Since the mouth of the tube could not be opened, two tubes were stacked and wound up. (3) Pinhole property: Holes of 1 mm or more were counted. Blow ratio: The maximum blow ratio that enables film formation. (4) Water vapor transmission rate: According to JIS-Z0208. (5) Tensile strength: According to JIS L-1096.

[0013]

[Table 1]

[0014]

As described above, according to the present invention, since pinholes are prevented and there are no pinholes, the quality is stable,
Secondary processability using this film is also improved, bubble molding is stable, film thinning and high-speed moldability can be improved,
Long length winding is possible, blocking is prevented, and a film made of polyurethane-based elastomer can be obtained without using a carrier sheet such as release paper in film forming, which simplifies the manufacturing process, improves handleability, and reduces manufacturing cost. Has effects such as reduction.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 inner layer extruder, 2 outer layer extruder, 3 die, 4 bubbles, 5 bubble inner layer, 6 bubble outer layer, 7 nip

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Claims (2)

[Claims] 1. (a) Thermoplastic polyurethane resin 35 to 9
0% by weight, (b) polyethylene resin 5 to 60% by weight, and (c) ethylene-propylene copolymer rubber 5 to 40
And a thermoplastic polyurethane resin or (a) thermoplastic polyurethane resin 35 to 90% by weight,
A thermoplastic polyurethane multi-layer film comprising a layer comprising (b) 5 to 60% by weight of a polyethylene resin and (c) 5 to 40% by weight of an ethylene-propylene copolymer rubber. (A) Thermoplastic polyurethane resin 35 to 9
0% by weight, (b) polyethylene resin 5 to 60% by weight, and (c) ethylene-propylene copolymer rubber 5 to 40
And a thermoplastic polyurethane resin or (a) thermoplastic polyurethane resin 35 to 90% by weight,
A thermoplastic polyurethane multi-layer film comprising: a layer composed of (b) 5 to 60% by weight of a polyethylene resin and (c) 5 to 40% by weight of an ethylene-propylene copolymer rubber. Production method.